Underground communication systems, such as radio-frequency (RF) and magnetic signal based communication systems, are subject to noise and other types of interference which hinder their intended operation. For example, the orientation of the transmitter and/or the relative positions of the transmitter and the receiver can affect the direction and strength of the transmitted field with respect to the receiver. Likewise, the intervening medium, for example, the atmosphere, earth, as well as man-made obstructions, can affect the transmitted magnetic field at the receiver in ways that are difficult or impossible to predict.
These characteristics may be especially detrimental to the performance of magnetic communication systems which utilize directional antennas, such as systems used in direction finding operations. Direction finding is the process of determining the location of a transmission source (usually radio or magnetic-based). Critical applications for direction finding include emergency rescue operations in harsh operating conditions, for example, on or around mountains or in underground mines. As RF transmissions are typically less effective through materials such as earth and rock, magnetic field based communications are often preferred. However, as set forth above, magnetic communication systems are subject to inaccuracies and signal power reductions which make direction finding operations difficult.
Improved magnetic communication systems are desired.